These are standard steel sink hold-down fasteners. The
T-shaped head slides in a groove and the metal clip grabs the underside of
the countertop.

There is a screwdriver slot in the lower end so the fastener can be
tightened.

This photo portrays how the clamps are supposed to work.
This device will work with a fairly wide range of counter thicknesses,
from about 1" to almost 2".

The metal clip bears against the underside of the counter
like this.

But... at the back of this sink, the counter had no
over-hanging lip. This posed a serious problem for which I initially had
no solution.

Then I decided to try cutting a groove in the back board of
the cabinet. I made two passes to create a slot about 3/16" wide,
enough for the sink clamp to fit into.

Another tool that would work for this is a Roto-Zip or possibly a Dremel moto-tool.
All you need is to cut out a little pocket for the "claw" part of the
clamp to grab onto.

The groove was about 1/2" below the top of the cabinet.
The clamp devices fit into the groove so I decided to go ahead and give it
a try.

Around the edge of the sink I used clear silicone (100%
silicone, not silicone/acrylic latex blend) for a sealant and
adhesive.

I made a fairly thick bead of silicone.

Many plumbers use "plumber's putty" for this job. There is
some debate over the merits of putty and silicone. I have a few
thoughts about plumber's putty...

In the past few years I have done numerous plumbing repairs that were made
possible by the old stand-by, Plumber's Putty. It is a vegetable-oil-based soft
material that can be easily rolled into long rope-like strands. (Do you remember
using Play-doh as a kid? Well its sole purpose is to prepare future plumbers
and handymen for the wonders of plumber's putty.) These strands can be wrapped
around many mating parts to form a gasket. And it seals great... until a year or
two has gone by and the putty dries out and turns brittle.

I believe plumber's putty is an old fashioned product that has a few purposes
(see my article on installing a bathroom
faucet and drain) but silicone is a new and very well proven material that
often performs much better than putty ever could.

The drawback of silicone caulk is
squeeze-out. It's difficult to get the exact amount of silicone
under the rim and have nothing ooze out after the basin is clamped
down. When excess silicone oozes out, the natural temptation is to wipe if off.
Resist that temptation! Let the silicone harden and then cut it
and scrape it away with a razor blade.

With the bead of silicone around the perimeter of the sink,
I set the basin in place.

Looking Up...

Under the sink, I carefully tightened the hold-down screws,
adjusting each a little at a time.

The clamps at the back tended to lean at an angle. As long
as they hold for 24 hours, until the silicone has fully cured, everything
will be fine.

There was some silicone ooze-out all around the edge of the
sink. In a way, ooze-out is desirable... it indicates that the silicone is being
packed in tightly, which creates a good seal.

After the silicone had fully cured, I used a sharp knife and a razor
scraper to trim off this excess. That procedure was a little time
consuming because the silicone stuck to the counter so well.

DO NOT be impatient and try to wipe off the excess silicone before it cures.
Wiping off uncured silicone is just about impossible. Wait at least an hour, and
then cut off the excess.

The completed sink installation, after the faucet had been
installed.

At this point there was still a large hole in the bottom of
each basin. This hole can be used for attaching a strainer basket or a
garbage disposal.